Do you like weeds in your lawn? When mulching, all you are doing is grinding up the weed seeds and dispersing all over your lawn. Bagging is a huge step to take to help slow down those pesky weeds. Bagging looks better as well.
Next we can talk about thatch and choking your lawn out. Okay I will go first. It stops water, fertilizer and air from getting down into the soil. If you can't see soil then you have a thatch problem or some good dense grass. Thatch also stops/slows spreading grasses from spreading. Rhizomes can't reach the soil.
Forget all the mulching hype about putting all those nutrients back into the soil nonsense. All that sales line is for is to sell more mowers. They don't care if you have a thatch issue. Mulching is an easier way to mow. And in LAZY America, remote controls and wireless ANYTHING items are king. If you can make ANY item, easier to use, it will sell like hotcakes.